From: Michal Hocko <mhocko@kernel.org>
To: Tejun Heo <tj@kernel.org>
Cc: "Roman Gushchin" <guro@fb.com>,
"Michal Koutný" <mkoutny@suse.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Johannes Weiner" <hannes@cmpxchg.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Kernel Team" <Kernel-team@fb.com>,
"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: Re: [PATCH 1/2] mm: memcg: switch to css_tryget() in get_mem_cgroup_from_mm()
Date: Thu, 14 Nov 2019 20:33:40 +0100 [thread overview]
Message-ID: <20191114193340.GA24848@dhcp22.suse.cz> (raw)
In-Reply-To: <20191114192018.GJ4163745@devbig004.ftw2.facebook.com>
On Thu 14-11-19 11:20:18, Tejun Heo wrote:
> Hello,
>
> On Thu, Nov 14, 2019 at 08:16:57PM +0100, Michal Hocko wrote:
> > Then what is the point of this function and what about all other users?
>
> It is useful for controlling admissions of new userspace visible uses
> - e.g. a tracepoint shouldn't be allowed to be attached to a cgroup
> which has already been deleted.
I am not sure I understand. Roman says that the cgroup can get offline
right after the function returns. How is "already deleted" different
from "just deleted"? I thought that the state is preserved at least
while the rcu lock is held but my memory is dim here.
> We're just using it too liberally.
Can we get a doc update to be explicit about sensible usecases so that
others can be dropped accordingly?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2019-11-14 19:33 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-06 22:51 [PATCH 1/2] mm: memcg: switch to css_tryget() in get_mem_cgroup_from_mm() Roman Gushchin
2019-11-06 22:51 ` [PATCH 2/2] mm: hugetlb: switch to css_tryget() in hugetlb_cgroup_charge_cgroup() Roman Gushchin
2019-11-07 0:26 ` Johannes Weiner
2019-11-07 2:31 ` Shakeel Butt
2019-11-07 15:44 ` Tejun Heo
2019-11-07 0:22 ` [PATCH 1/2] mm: memcg: switch to css_tryget() in get_mem_cgroup_from_mm() Johannes Weiner
2019-11-07 1:25 ` Shakeel Butt
2019-11-07 1:43 ` Johannes Weiner
2019-11-07 1:43 ` Roman Gushchin
2019-11-07 2:21 ` Shakeel Butt
2019-11-07 2:28 ` Shakeel Butt
2019-11-07 12:21 ` Michal Hocko
2019-11-07 15:43 ` Tejun Heo
2019-11-07 16:42 ` Roman Gushchin
2019-11-07 17:02 ` Michal Hocko
2019-11-07 22:41 ` Roman Gushchin
2019-11-08 8:53 ` Michal Hocko
2019-11-07 15:43 ` Tejun Heo
2019-11-13 16:29 ` Michal Koutný
2019-11-13 17:08 ` Roman Gushchin
2019-11-14 19:16 ` Michal Hocko
2019-11-14 19:20 ` Tejun Heo
2019-11-14 19:33 ` Michal Hocko [this message]
2019-11-14 19:37 ` Tejun Heo
2019-11-15 17:40 ` Michal Hocko
2019-11-15 17:45 ` Tejun Heo
2019-11-15 17:47 ` Michal Hocko
2019-11-15 17:48 ` Tejun Heo
2019-11-15 18:03 ` Michal Hocko
2019-11-15 18:07 ` Roman Gushchin
2019-11-18 9:43 ` Michal Hocko
2019-11-15 18:13 ` Roman Gushchin
2019-11-21 15:28 ` Michal Koutný
2019-11-22 8:20 ` Michal Hocko
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